The Pentair 460736 MasterTemp 400 has proven itself to be one of the best pool heaters on the market. We’ve recently reviewed the Hayward H400FDN — 400,000 BTU pool heater, if you want to compare the models. The Hayward H400FDN pool heater is more widely used but both are powerful units that can heat your pool quickly. Both are natural gas heaters.
You should know that you won’t find a heater that’s been unanimously named “the best pool heater.” It doesn’t exist. Pool systems are complex and many customers don’t know how to properly maintain their pool equipment and wrongly blame it on the equipment. But that’s another issue which I discuss later. It’s essential that you hire a certified professional to install it correctly.
There are some excellent pool heaters on the market, and the Pentair MasterTemp is one of the them. The Hayward H400FDN is another.
Pentair MasterTemp 400
This review will focus on the details for the Pentair MasterTemp 400 to help you decide if it’s the right pool heater for your needs. I’ll also cover the details of the other models to make sure you’re selecting the correct size. We cover it all here.
If you’re a pool owner you’re already familiar with the reputation and quality that Pentair (Aquatic Systems) consistently delivers with their swimming pool products. They manufacture a variety of pool products that include: high-performance pool pumps, filters, heaters, cleaners, lights, automation systems and more.
Pentair is at the top of the list of best pool equipment manufacturers as they also own Sta-Rite. Hayward and Pentair are the top 2 brands, alongside Zodiac, which owns Jandy, Polaris and more. As with most industries, there are a few big players who own the majority of the brands.
Pentair is a massive global company with a wide industry focus which they describe as: water and fluid solutions, valves and controls, equipment protection and thermal management products.
The Pentair MasterTemp 400 pool heater comes in three different models:
- Pentair 460736 :Standard model: Copper heat exchanger.
- Pentair 460805 : Heavy-duty (HD) : Copper-nickel exchanger stands up to the harshest of applications, like low pH, high flow or heavy use.
- Pentair 460775 : MasterTemp: (ASME Certified) Increased durability. More resistant components, such as: thicker CU heat exchanger and metal headers.
Note: Standard Copper Heat Exchanger 84% Efficient. Heavy-duty (HD) Cupro-Nickel Heat Exchanger 82% Efficient.
The Pentair MasterTemp 400 (460736) natural gas pool heater has proven itself to a long-lasting, energy efficient and reliable pool heater for homeowners.
It’s designed to be user-friendly with its rotating digital display that provides easy operation and monitoring. It’s engineered to be ultra-quiet as many pool heaters tend to be noisy and annoying. Thankfully, the Pentair MasterTemp 400 won’t bother you when you’re lounging in your swimming pool.
The control panel displays the water temperature, and five led lights give you system status and indicates when your pool heater needs servicing.
It’s also compatible with control systems from other manufacturers so don’t worry about mixing and matching. They can communicate with one another.
Materials | Pentair MasterTemp 400
When it comes to buying the best pool heater you have to consider the materials of the heater itself and the type of pool you own. Some materials will stand up better to salt water pools than others. For example, the Pentair MasterTemp 400 HD is made with a copper-nickel (cupronickel) alloy which is more durable than standard copper because the addition of nickel to the copper dramatically improves the overall strength and corrosion resistance while allowing the alloy to remain ductile — the ability to deform, bend or stretch under stress while maintaining it’s strength.
Copper-nickel is typically used for marine applications due to their excellent resistance to seawater corrosion. Bottom line: The Pentair MasterTemp 400 HD will definitely last longer than the standard MasterTemp 400 copper model but the HD model also will cost you more money. That’s obviously the trade-off when buying a swimming pool heater: cost vs durability.
Pool heaters are expensive and it seems that many manufacturers today are cutting costs by reducing the amount of materials used in their standard products and charging extra for what you used to get years ago. My point is that the HD model of the Pentair MasterTemp is built to a higher quality standard which, in my opinion, should be the default model available.
These pool heaters are expensive so if you’re going to buy one, you’re better off spending a little more for the higher quality model, but if you’re an average homeowner I suggest you stick with the standard model. If your pool gets a lot of consistent usage all-year-round; like a commercial pool or you’re running a salt-water system, then I recommend you splurge and get the MasterTemp 400 HD model. The HD stands for “Heavy-Duty.”
Ultimately, it’s up to you as the pool owner to ensure that the Pentair 460736 MasterTemp 400 is installed properly and your pool setup is robust enough to provide the proper amount of natural gas. Also, you want to make sure that your pool components will work efficiently with the pool heater.
Read the MANUAL as well. Everything you need to know is there, including INSTALLATION information.
Hire a pool technician and get it done right. Honestly, you’re not saving any money if you incorrectly install your Pentair MasterTemp 400. It’s a false sense of satisfaction. I believe in the old adage: Measure twice, cut once.
Here’s a list of the buttons and their functionality for the Pentair MasterTemp 400:
- POOL ON : Press this button to govern heater operation by the pool temperature setting.
- SPA ON : Press this button to govern heater operation by the spa temperature setting.
- HEATER OFF : Press this button to switch off the heater.
- TEMP Up : Press this button to raise the temperature setting.
- TEMP Down : Press this button to lower the temperature setting.
Shipping | Pentair MasterTemp 400
As you know, this is an expensive pool heater and one of the most important things to ensure that the Pentair MasterTemp 400 is in how it’s handled when it’s shipped. Based on my research, it seems that some customers had their pool heater delivered improperly. For example, not on a pallet.
Amazon has fixed the issue as they’re now shipping the Pentair MasterTemp 400 correctly; making sure that the heater is shipped on a pallet as to avoid damage during transportation. It weighs between 120 to 130 lbs, depending on the model. It can and should only be shipped on a pallet.
MasterTemp Installation | Do It Right
As with all pool equipment, it’s important to maintain the proper water chemistry in order to preserve and maintain the life of your heater, pump, and filter. One thing you need to understand about online customer reviews is that the majority of “happy” owners don’t complain. Why? Because they’re satisfied and aren’t motivated to write a review.
The people who do complain are the occasional customers who receive a faulty unit or perhaps install the unit incorrectly. Or don’t maintain the proper water chemistry. For example, the Pentair MasterTemp 400 requires a large gas line, do you ? I suspect that the majority of issues that customers have with the Pentair 460736 MasterTemp 400 is due to having an inadequate pool system — or they fail to maintain the correct pool chemistry.
If your PH is low then your water essentially acid, and will quickly destroy your heat exchanger. This is your fault, not the fault of the pool heater. I can’t stress this point enough: If you don’t know how to maintain your pool hire a professional or pay someone to teach you.
My recommendation is to have a professional pool technician install the MasterTemp pool heater for you and even better, have them check your pool system before ordering.
The Pentair 460736 MasterTemp 400 is a incredibly fast and efficient pool heater that will heat your pool quickly, assuming you set it up properly and you buy the right BTU size. The product is very good but the bigger question you need to ask yourself is: Is your current pool system setup efficient?
There are far too many people who ‘think’ they know what they’re doing when it comes to home pool installations but they end up installing a component incorrectly and then they go online and complain about the problems they encounter afterwards. Don’t be one of those guys (or girls)! Pool systems are complicated. Take the responsibility to get your pool components installed correctly the first time.
What’s your pool size?
Use Pentair’s handy pool volume calculator. It’s simple to use. Just input the data and it will tell you your pool volume. Verify your pool size before making a purchase. You need to know the real numbers in order to buy the right Pentair MasterTemp model. Too many pool owners are incorrect about their actual pool size and end up buying the wrong sized pool heater.
It’s always better to buy the next model up rather than buy one that doesn’t have enough heating capacity. In the long run you end up having a longer lasting unit because you’re not pushing it to its maximum capacity day after day.
Documents | Pentair MasterTemp 400 | Pool Heater
- MANUAL & INSTALLATION — Pentair MasterTemp 400
- BROCHURE — Pentair MasterTemp 400
- INSTALLATION CHECKLIST — Pentair MasterTemp 400
- BYPASS ACCESS PLUG KIT — Pentair MasterTemp 400
- DIMENSIONS DIAGRAM — Pentair MasterTemp 400
*Note: These documents are applicable to all MasterTemp pool heater models.
The manual specifically states:
Water chemistry should follow good swimming pool water chemistry practices. When using a chlorinator, install it down stream from the heater and at a lower level than the heater outlet.
Install a corrosion resistant positive seal “Check Valve”, (P/N R172288), between the heater and the chlorinator to prevent concentrated chemicals from back-siphoning into the heater. Back-siphoning is most likely to occur when the pump stops, creating a pressure-suction differential.
Do NOT sanitize the pool by putting chlorine tablets or sticks into the skimmer(s). When the pump is off, this will cause a high concentration of chlorine to enter the heater, which could cause corrosion damage to the heat exchanger.
Three major items that can cause problems with your pool heater are: improper pH, disinfectant residual, and total alkalinity. These items, if not kept properly balanced, can shorten the life of the heater and cause permanent damage.
Heat exchanger damage resulting from chemical imbalance is not covered by the warranty.
As I said, get a professional installation and maintain proper water chemistry and the Pentair MasterTemp pool heater will last you a long time.
Features (Pentair MasterTemp 400):
- Heats up fast so no long waits before enjoying your pool or spa.
- Best-in-class energy efficiency.
- Manual gas shut-off when service is required.
- Eco-friendly MasterTemp is certified for low NOx emission and outperforms industry standards.
- Rotating digital display allows for easy viewing.
- Tough, rust-proof exterior handles the heat and weathers the elements.
- Weight: 120 to 130 lbs (depending on model).
- Pre-mixed system with a highly efficient air and gas mixture enables the heater to heat up rapidly.
- Easy to operate: Hot surface ignition (no pilot light) and push-button, digital controls.
- Has a series of safe features, including: A water pressure switch that senses the pump is running to prevent overheating, high limit switches will shut off the heater if water temperatures exceeds factory-set limits, manual gas shut-off when servicing, stack flue sensor guards against overheating.
- Approved for installation on combustible surfaces.
- Pentair MasterTemp size: 36 x 25 x 30 inches (see diagram)
Choose the right Pentair MasterTemp heater for your POOL:
Choose the right Pentair MasterTemp heater for your SPA:
NOTE: The chart is based on a 30°F (16.6°c) temperature rise, discounting losses and only based on heat required to raise temperature in minutes.
Other Common Natural Gas Pentair MasterTemp Models:
- Pentair MasterTemp 460792 — 175,000 BTU
- Pentair MasterTemp 460730 — 200,000 BTU
- Pentair MasterTemp 460771 — 250,000 BTU ASME
- Pentair MasterTemp 460732 — 250,000 BTU
- Pentair MasterTemp 460734 — 300,000 BTU
How does the Pentair MasterTemp 400 work?
Precisely aligned orifice plates measure the air and gas going into the mixer. The blower draws the air and gas through the mixer and forces it into the burner’s flame holder. A sealed heat exchanger encompasses the flame holder, discharging exhaust gases out the flue.
Two inch (2″) PVC water piping connects directly to the manifold/header on the heat exchanger using 2″ PVC slip unions (provided) with the heater. The outer manifold always stays cool; no heat sinks are required.
A thermal regulator and an internal bypass valve regulate the water flow throughout the heat exchanger to maintain the proper outlet temperature. The heater operator control panel board is located on top of the heater.
Water Flow Rate | Pentair MasterTemp Pool Heaters
NOTE: If the heater is plumbed in backwards, it will continuously cycle. Ensure that the piping from the filter is not reversed when installing heater.
GPM = Gallons per minute.
Recommended Water Connections | Pentair MasterTemp
Pentair recommends the following (see diagram above): The filter pump discharges to the filter, the filter discharges to the heater, and the heater discharges directly to the pool or spa.
You should install a manual bypass valve across the heater when the pump flow exceeds 120 GPM (454 LPM).
Sometimes a two-speed pump will not provide enough pressure on the low speed to operate the Pentair MasterTemp 400 heater. If this occurs, run the pump at high speed only to operate the heater. If this does not solve the problem, do not try to run the heater. Instead, correct the installation.
Never operate the heater while an automatic pool cleaner is also operating. If the circulation pump suction is plugged (for example by leaves), there may not be enough water flow going to the heater. Do not rely on the pressure switch in this case.
As you can see, there are a lot of things that could go wrong, which is why I recommend hiring a pool technician to do it for you. To learn all the technical details of installation then please refer to the MANUAL at all times.
Gas Line Installation
Before installing the gas line, be sure to check which gas the heater has been designed to burn. This is important because different types of gas require different gas pipe sizes. The rating plate on the heater will indicate which gas the heater is designed to burn.
The gas meter should be checked to make sure that it will supply enough gas to the heater and any other appliances that may be used on the same meter. The gas line from the meter will usually be of a larger size than the gas valve supplied with the heater. Therefore a reduction of the connecting gas pipe will be necessary. Make this reduction as close to the heater as possible.
Gas Pressure | Pentair MasterTemp Pool Heater
The heater requires a gas supply of not less than 4″ (10.2 cm) wc and not more than 14″ (35.6 cm) wc. Gas supply pressures outside of this range may result in improper burner operation. A minimum flowing or dynamic inlet pressure (while the heater is running) of 4″ (10.2cm) wc is required to maintain input rating with no more than a 2” pressure drop between static and dynamic.
NOTE: Never install the gas line union inside the heater cabinet. This will automatically void your warranty.
Outdoor Venting Guidelines
The Pentair MasterTemp must be at least 3 ft. above any forced air inlet located within a 10 foot radius.
Vent Termination: Must be located 6″ away from the building wall and the following distances away from any building wall openings, included but not limited to vented eaves, doors, windows, gravity air inlet: 4 ft. below, 4 ft. horizontally
This pool heater can also be installed indoors. Please refer to the MANUAL for all the specifics.
The Pentair MasterTemp 400 can be installed as a Category I or Category III appliance.
Recommended Compatible Components:
Pentair 011018 IntelliFlo | Variable Speed Pump
If you haven’t upgraded your pool pump to a variable speed pump I would suggest making the switch. Over the long run it will definitely save you lots of money in energy costs. It’s far more efficient. We’ve done a comprehensive review of the Pentair 011018 IntelliFlo Variable Speed Pump so I won’t repeat it here.
Just read the article and decide for yourself if it makes sense for you at this point in time. Either way, if you decide to wait until your current pump dies then make the purchase at that time. Well, that’s my recommendation. If you decide to stick with an outdated one-speed pump that’s up to you.
Another bonus is that many utility companies provide a rebate if you buy one. Yes, it’s really that efficient. You can find out about the rebates and everything you need to know in the article.
All functions controlled with easy, one-button access from the self-contained load center or optional controllers. No need to memorize operating sequences, open and close valves, or reset time clocks and thermostats.
Optional controllers for added convenience: Indoor control panel (for 4 or 8 circuit systems), a wireless controller (for 4 or 8 circuit systems), a QuickTouch 4-function wireless remote, a Four-function spa-side remote, a 4-button spa side remote, and iS10 spa-side remote.
Built-in diagnostics include automatic verification of the display, microprocessor, switches, indicators, relay outputs, valve outputs, sensor inputs, and communication ports as well as a diagnostic screen that reports failures for troubleshooting and repair purposes
Includes: Easy Touch 4 Control Panel for Pool and Spa Combinations (dual bodies of water with one set of equipment). 150 Amp breaker base with space for ten 1″ breakers. 2 Actuator Valves.
- Easy, one-button access from the self-contained load center or optional controllers.
- Optional controllers for added convenience.
- Includes 125 Amp Breaker Base.
- UL and CUL approved.
Videos | Pool Heater Tips and Troubleshooting
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